Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
Not a member yet
4476 research outputs found
Sort by
Carbon flow in the plant-soil-microbe continuum at different growth stages of maize grown in a Mollisol
No full textUnderstanding the photosynthetic carbon (C) dynamics in the plant-soil-microbe continuum is critical to the C sequestration in soils. However, such information is limited in maize (Zea mays L.) in Mollisols. Pot-grown maize was labelled with (CO2)-C-13 at the 10-leaf, 15-leaf, heading, milk and dent stages to investigate the photosynthetic C flow in a maize-soil system and its contribution to soil organic carbon (SOC) in Mollisols. The majority of fixed C-13 was recovered in shoots, ranging from 44.7% to 78.6%. The allocation of C-13 fixed at different growth stages to belowground (roots and soil) gradually decreased over the growing period, indicating that the strength of root C sink is stronger at the early stages. However, the proportion of C-13 in dissolved organic C and microbial biomass C to that in SOC significantly increased as the growth stages advanced. Over the entire growth period, the contribution of root-derived C to SOC was estimated to be 5461 mg C plant(-1) growth period(-1), of which approximately 79% was synthesized during the vegetative stages. Therefore, the input of photosynthetic C by maize plants into SOC mainly occurred during the younger stages of the plant, favouring the storage of SOC in Mollisols
Warming in Spring and Summer Lessens Carbon Accumulation over the Past Century in Temperate Wetlands of Northeast China
No full textDeciphering how climate change affects carbon accumulation rates (Carbon(sq)) is vital to understanding climate-carbon pool feedbacks on century scales. Carbon, nitrogen, and phosphorus accumulation rates were estimated by isotopic Pb-210 dating technology from 10 temperate wetlands in Northeast China. Soil carbon, nitrogen and phosphorus accumulated at average rates of 164.75 gC m(-2) yr.(-1), 5.61gN m(-2) yr.(-1), and 1.83gP m(-2) yr.(-1) during the past 153 years, respectively. Climate warming tended to grow increasing along the latitude and was faster in winter than in summer. Asymmetrical warming in spring and summer would lessen Carbon(sq) and oppose wetland functions as carbon sinks. High positive correlation coefficients between precipitation and Carbon(sq) meant that increasing precipitation facilitated Carbon(sq) greatly. Conversely, it was shown that warming in conjunction with subsequent drought was impairing Carbon(sq) in wetlands. There were strong positive feedbacks between climate warming and Carbon(sq) that could weaken wetlands functioning as carbon sinks in Northeast China
Root Damage under Alkaline Stress Is Associated with Reactive Oxygen Species Accumulation in Rice (Oryza sativa L.)
No full textAlkaline stress (high pH) severely damages root cells, and consequently, inhibits rice (Oryza sativa L.) seedling growth. In this study, we demonstrate the accumulation of reactive oxygen species (ROS) in root cells under alkaline stress. Seedlings of two rice cultivars with different alkaline tolerances, 'Dongdao-4' (moderately alkalinetolerant) and 'Jiudao-51' (alkaline-sensitive), were subjected to alkaline stress simulated by 15 mM sodium carbonate (Na2CO3). Alkaline stress greatly reduced seedling survival rate, shoot and root growth, and root vigor. Moreover, severe root cell damage was observed under alkaline stress, as shown by increased membrane injury, malondialdehyde accumulation, and Evan's Blue staining. The expression of the cell death-related genes OsKOD1, OsHsr203j, OsCP1, and OsNAC4 was consistently upregulated, while that of a cell death-suppressor gene, OsBI1, was downregulated. Analysis of the ROS contents revealed that alkaline stress induced a marked accumulation of superoxide anions (O-2(center dot-)) and hydrogen peroxide (H2O2) in rice roots. The application of procyanidins (a potent antioxidant) to rice seedlings 24 h prior to alkaline treatment significantly alleviated alkalinity-induced root damage and promoted seedling growth inhibition, which were concomitant with reduced ROS accumulation. These results suggest that root cell damage, and consequently growth inhibition, of rice seedlings under alkaline stress is closely associated with ROS accumulation. The antioxidant activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase increased under alkaline stress in the roots, probably in response to the cellular damage induced by oxidative stress. However, this response mechanism may be overwhelmed by the excess ROS accumulation observed under stress, resulting in oxidative damage to root cells. Our findings provide physiological insights into the molecular mechanisms of alkalinity-induced damage to root cells, and will contribute to the improvement of alkaline stress tolerance in rice plants
Sources of monsoon precipitation and dew assessed in a semiarid area via stable isotopes
No full textPrecipitation is usually the primary source of water for the hydrological cycle in a semiarid area. However, dew occurs frequently and affects water circulation dramatically in the west of Jilin Province in China. Measurements of the amount of dew formed and precipitation were carried out from July 2012 to October 2013 in the Momoge Natural Reserve. The results indicated that moisture from primary precipitation in the summer originated from the East Asian monsoon and was affected by the atmospheric circulation in the middle and high latitudes of Eurasia in the winter. The dew amount was approximately 19.44 mm (approximately 5% of the total rainfall amount), consisting of the evapotranspiration in the local area and atmospheric moisture. Dew also supplies nutrients to the local vegetation. The maximum contribution of total nitrogen, total phosphorus, and potassium in unit corn area could reach 288.60, 27.46, and 291.63 mg/m(2) in half a month, respectively. The wind speed, relative humidity, and lowest temperature were the primary factors that dramatically affected dew formation and amount. As an additional source of fresh water, dew not only had a positive impact on the ecosystem in arid and semiarid zones but also played an important role in the local water cycle and other ecological processes. This research has important implications for water circulation and land use management
Spatio-temporal patterns of soil organic carbon and pH in relation to environmental factors-A case study of the Black Soil Region of Northeastern China
No full textThe Northeastern Black Soil Region plays a key role in food supply in China. Identifying spatio-temporal variation of soil properties as influenced by environmental factors has become essential for future agricultural development. A total of 5891 topsoil samples (0-20 cm) were collected and soil organic carbon (SOC) and pH were measured in the Jilin Province. Geostatistics, multiple linear regression, and redundancy analysis (RDA) were used to highlight the spatio-temporal patterns of SOC and pH and determine the relationship with environmental factors. Results showed that from 1980 to 2010 average level of SOC increased by 2.68 g kg(-1) (p 0.05) throughout the province. Environmental factors could explain 64% and 78% of the spatial patterns of SOC and pH, respectively. The principal factors impacting SOC and pH included: precipitation, gully density, forested land and grain yield. There was significant covariation between natural and human factors in forming these spatial patterns. Anthropogenic disturbance had a larger influence on the distribution of SOC than on the distribution of pH
Effects of land use/land cover on diurnal temperature range in the temperate grassland region of China
No full textAs a fragile ecological zone, the temperate grassland region of China has experienced dramatic land use/land cover (LULC) changes due to human disturbances. So far, the impacts of LULC change on climate especially the diurnal temperature range (DTR) in this region are still not well understood. Based on the OMR (observation minus reanalysis) method, this study investigated the effects of LULC on DTR in the temperate grassland region of China. Considering the possible uncertainty of the results due to spatial resolution of the reanalysis dataset, two reanalysis datasets with different spatial resolutions were utilized. Results showed that LULC generally contributed to the decline of DTR in the temperate grassland region of China during 1980 to 2005. Due to different warming effects on monthly maximum temperature (Tmax) and minimum temperature (Tmin), grassland and forest tend to slightly decrease monthly DTR (approximately -0.053 to -0.050 degrees C/decade and approximately -0.059 to- 0.055 degrees C/decade, respectively), while bare land has a slightly positive effect on DTR (approximately 0.018-0.021 degrees C/decade). By contrast, cropland and urban tend to slightly decrease Tmax, obviously increase Tmin and thus result in a rapid decline of DTR (approximately -0.556 to -0.503 degrees C/decade and approximately -0.617 to -0.612 degrees C/decade, respectively). In the temperate grassland region of China, grassland vegetation changes due to human disturbances can have some effects on DTR mainly by changing the Tmax. Conversion from grassland to cropland could decrease the DTR by slowing down the increase of Tmax. But the conversion from grassland to bare land, as well as the reduction of grassland vegetation cover will increase Tmax, and consequently the DTR. The results suggest that grassland degradation is likely to result in daylight warming and increased DTR in the temperate grassland region of China. (C) 2016 Elsevier B. V. All rights reserved
The temperature sensitivity of organic carbon mineralization is affected by exogenous carbon inputs and soil organic carbon content
No full textTemperature sensitivity of organic carbon (C) mineralization is affected by C inputs, but predicting the magnitude of the response remains a challenge. We investigated how temperature and exogenous C inputs affected the apparent organic C mineralization in soils with a range of soil organic C (SOC) contents. Soils with 2.9, 4.0, and 6.8% SOC content were incubated with or without C sources (either plant residues or glucose), at two temperatures (15 or 25 degrees C) for 120 days. Apparent organic C mineralization was significantly affected by SOC content and C inputs. Cumulative CO2 production in soils with a higher SOC content was less sensitive to C inputs. Glucose was always more effective in stimulating CO2 production than plant residue. Without exogenous C inputs, the temperature sensitivity of organic C mineralization (described by Q(10) value) was higher in the 4.0% SOC soil (2.31) than in the 2.9% (1.12) and 6.8% SOC soils (130). The addition of exogenous C decreased Q(10) values by up to 131% in the 4.0% SOC soil, which was not observed in other two soils. In general, C inputs increased the Q(10) of the estimated active (C-a) and stable C (C-s) pools in all the tested soils, especially the C-s pool in the 4.0 and 6.8% SOC soils. Results indicated that the effect of C inputs on apparent organic C mineralization (either stimulatory or inhibitory) is influenced by SOC content and C source, and that temperature sensitivity of organic C mineralization in the presence of exogenous C is highly sensitive to SOC content. (C) 2017 Elsevier Masson SAS. All rights reserved